The Matrix chips are programmed with an external programmer connected to a PC. Once the bios is programmed you can put the modchip in the XBOX.
Mode 1, Chip disabled, switch 1 & 2 ON
Mode 2, Mod bios always loads, switch 1 OFF, 2 ON
Mode 3, Mod bios loads first, eject loads original bios, switch 1 ON, 2 OFF
Mode 4, Write enable (used for flashing), switch 1 & 2 OFF.